(a) Field of the Invention
The present invention relates to a cathode active material for a lithium rechargeable battery, a method of manufacturing the same, and a lithium rechargeable battery including the same.
(b) Description of the Related Art
With respect to the recent trend of a reduction in size and weight of portable electronic devices, demand for an increase in performance and capacity of a battery used as a power source for the devices has increased.
The battery generates electric power by using a material which can electrochemically react with a cathode and an anode. A representative example of the batteries includes a lithium rechargeable battery generating electrical energy by a change in chemical potential when lithium ions are subjected to intercalation/deintercalation in the cathode and the anode.
The lithium rechargeable battery is manufactured by using a material where reversible intercalation/deintercalation of the lithium ions is feasible as cathode and anode active materials, and charging an organic electrolyte solution or a polymer electrolyte solution between the cathode and the anode.
A lithium complex metal compound is used as the cathode active material of the lithium rechargeable battery, and complex metal oxides such as LiCoO2, LiMn2O4, LiNiO2, LiNi1-xCoxO2 (0<x<1), and LiMnO2 have been researched as an example thereof.
Among the cathode active materials, a Mn-based cathode active material such as LiMn2O4 and LiMnO2 can be easily synthesized and is relatively inexpensive, and has the highest thermal stability during over-charging as compared to other active materials, and a low degree of pollution to the environment, and thus is attractive, but has a drawback in that capacity thereof is small.
Further, LiNiO2 has a battery characteristic of the highest discharging capacity among the aforementioned cathode active materials, but has a drawback in that it is difficult to synthesize LiNiO2. Further, a high oxidation state of nickel becomes a cause of deterioration of the life-span of both a battery and an electrode, and there are problems in that self-discharging is severe and reversibility is poor. Moreover, since stability is not completely secured, there is difficulty in commercialization.
Currently, LiCoO2 is generalized as an active material having a particle diameter of about 10 μm, but does not ensure sufficient energy density.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.